I. Field
The following description relates generally to communication systems, and more particularly to Preamble Extensions.
II. Background
In order to address the issue of increasing bandwidth requirements that are demanded for wireless communications systems, different schemes are being developed to allow multiple user terminals to communicate with a single access point by sharing channel resources while achieving high data throughputs. Multiple Input, Multiple Output (MIMO) technology represents one such approach that has recently emerged as a popular technique for next generation communication systems. MIMO technology has been adopted in several emerging wireless communications standards such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11 denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE 802.11 committee for short-range communications (e.g., tens of meters to a few hundred meters).
The new 802.11 VHT (Very High Throughput) is a new standard, which operates in MIMO mode. MIMO technology may be used by a transmitter to communicate with several receivers using Spatial-Division Multiple Access (SDMA). SDMA is a multiple access scheme which enables multiple streams transmitted to different receivers at the same time to share the same frequency spectrum. Within any given stream, there are data packets that contain both data and preamble. Designing efficient preambles are needed to handle the new technology.